Compounds of structure similar to that of the compounds of the invention are described in U.S. Pat. No. 5,254,569 as analgesics, diuretics, anticonvulsivants, anesthetics, sedatives and cerebroprotective agents, via a mechanism of action on the opiate receptors. Other compounds of similar structure are described in patent application EP-0 499 995 as 5-HT3 antagonists that are useful in the treatment of psychotic disorders, neurological diseases, gastric symptoms, nausea and vomiting.